CoChat
Sign Up
Cited by 16Thyroid Disorders and TreatmentsThyroid and Parathyroid SurgeryAdrenal Hormones and Disorders

Levothyroxine absorption test results in patients with TSH elevation resistant to treatment

Yildirim Simsir, Ilgin, Soyaltin, Utku Erdem, Ozgen, Ahmet Gokhan·2019·Endocrine
DOI 10.1007/s12020-019-01889-x
Open this paper in CoChat — free account

Abstract

Introduction Persistent elevation of thyroid-stimulating hormone (TSH) is common in endocrinology practice in patients undergoing replacement or suppression therapy with levothyroxine sodium (LT4). After examining the causes of this condition, LT4 absorption test is recommended. In this report, we wanted to share our results of LT4 absorption test in patients with elevated TSH levels.Materials-methods The files of patients who presented to our clinic between 2015 and 2018, whose TSH elevation continued despite high-dose LT4 therapy, and who underwent absorption test were reviewed retrospectively.Results Levothyroxine sodium absorption test was applied to five patients. Absorption test revealed LT4 malabsorption in two patients and pseudomalabsorption in the other three patients.Discussion When all published pseudomalabsorption cases were considered, it has been stated that at least 2.5 times increase in basal fT4 level may exclude malabsorption. The formula we used has been implemented by Cleveland Clinic since 2014.Conclusion In cases where TSH normalization is not achieved despite high doses of LT4 therapy, LT4 absorption test is an easy test for administration and interpretation and prevents unnecessary medical treatments and examinations.

Integrity signals

Registry

Crossref · 10.1007/s12020-019-01889-x

Cites

19 of 19 references verified0 citation errors · 0 not checkable

Statistics

Recomputing p-values needs the paper’s full text.

Claims the paper makes

This paper’s full text isn’t openly available, so its claims and self-check weren’t run. The registry and citation checks still apply.

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The increase in FT4 levels compared with baseline also indicates absorption ability, although the threshold value ranges from 50% to 250% in different studies.

    “The increase in FT4 levels compared with baseline also indicates the absorption ability, although the threshold value ranges from 50% to 250% in different studies (132, 133).”

    From Levothyroxine: conventional and novel drug delivery formulations. (2023) · cites this paper as [132]

  • In 5 patients evaluated with the LT4 absorption protocol, 2 had impaired absorption (<60%) with the underlying cause revealed in subsequent examinations, and the remaining 3 were diagnosed with pseudomalabsorption.

    “Simsir and colleagues used the protocol to evaluate the absorption ability in 5 patients (132). Two patients had impaired absorption (<60%) and the underlying cause was revealed in subsequent examinations. The remaining 3 individuals were diagnosed with pseudomalabsorption.”

    From Levothyroxine: conventional and novel drug delivery formulations. (2023) · cites this paper as [132]

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Related

Authors
Yildirim Simsir, I., Soyaltin, U. E., & Ozgen, A. G.
ORCID
Venue
Endocrine
Publisher
Springer Science and Business Media LLC
Published
2019-03-13
Volume
64
Issue
1
Pages
118-121
ISSN
  • 0969-711X (ISSN-L)
  • 1355-008X
  • 1559-0100
DOI
10.1007/s12020-019-01889-x
OpenAlex
W2921412141
Cited by
16
References
19
Citations by year
2026: 1 · 2025: 1 · 2023: 5 · 2022: 4 · 2021: 2 · 2020: 2 · 2019: 1
FWCI
1.83
Type
journal article
Language
en
Open access
closed
Licence
www.springer.com/tdm (tdm)
Locations
  • Endocrine (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Health Sciences › Medicine › Surgery › Thyroid and Parathyroid Surgery
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Adrenal Hormones and Disorders
Keywords
TSH elevation, thyroid-stimulating hormone, levothyroxine therapy, thyroid hormone replacement
MeSH terms
Humans, Hypothyroidism, Pituitary Diseases, Retrospective Studies, Thyrotropin, Thyroxine

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review